Conventional bearing housings well known in the mechanical arts have grease ports through which grease or other lubricant may be injected into the housing for reducing friction between the bearing and the shaft rotating within the housing. Typically, these grease ports are threaded apertures designed to receive a threaded grease fitting. The grease fitting is removably insertable into the grease port, and includes an axial bore specially configured to permit grease or other lubricant to be injected through the fitting and into the bearing housing without leakage. Notwithstanding this feature, bearings within such housings are prone to fail over time from excessive wear and heat generated by friction between the bearing and the rotary shaft or other objects in contact with the bearing.
U.S. Pat. No. 3,603,280 to Zahuranec discloses a fitting which works in conjunction with a static pressure line, a temperature sensitive fusible plug, and a pressure sensitive alarm to warn of a component's increased temperature, increased temperature in the bearing housing signifying impending bearing failure. Bearing failure can cause equipment to become inoperable and may be hazardous, depending upon the particular function of the apparatus which includes the bearing. Because of the importance of maintaining functional equipment where ever bearings are employed, the ability to reliably and continuously monitor bearing performance during equipment operation and to forecast bearing failure would constitute a significant contribution to equipment maintenance and safety, especially if such a contribution could be made without otherwise affecting the functionality or design of the apparatus or housing containing the monitored bearing.